Respostas

2013-11-10T20:50:26-02:00
X/q+x+x.q=19
x(1/q+q)=19-x

(x/q-1,x,xq é uma PA)
x-(x/q-1)=xq-x
x/q+xq =2x+1
x(1/q +q)=2x+1

Bom,daí 19-x=2x+1
x=6

x(1/q +q)=2x+1
(1/q+q) =[2(6)+1]/6
1/q+q =13/6
6+6q² =13q
O delta=25,raíz...5
q=(13±5)/12
q' =18/12 =3/2
q" =8/12 = 2/3

Para q=3/2
x/q =6/(3/2) =4
x=6
xq=6(3/2) = 9
PG(4,6,9)
(a1+a2)-a3 =(4+6)-9 = 1